How Small Is Too Small A Room For Surround Speakers?

Question: My home theater is located in a 12 x 12- foot spare bedroom. A local A/V dealer told me this room is too small to install back surround speakers for 7.1. Is this true? If so, is there a speaker that can function as both surround and rear speakers so both channels can be hooked up to the same pair of surround speakers (thereby getting a 7.1 from a 5.1 speaker system)? STEVE TEMPLE / VIA E-MAIL

Answer: That space is definitely on the small side for 7.1, but installing back surround speakers is possible as long as your sofa isn’t placed directly against the rear wall. When I ran your letter by Sound & Vision’s speaker gurus Daniel Kumin and Brent Butterworth, however, they recommended that you not only avoid stuffing back surround speakers into such a tight space, but that you also consider using dipolar models for your side surround channels. A dipolar surround, which can create a more diffuse sound field than a standard direct-radiating speaker, is a better option for small rooms, where surround speaker localization can be an issue.

Another — and potentially much bigger — problem that both of our gurus pointed out is your room’s square dimensions, which are likely to generate a bass hump in the 90- to 95-Hz range. They suggest that you set your receiver’s crossover to 100 Hz and that you set your sub’s crossover to low-pass-filter signals at 80 Hz. You might also consider Audyssey EQ, a processing mode built into many newer receivers that can help to smooth out bass problems.

Since you asked, we do know of a few surround speakers we know of that can be wired to deliver simultaneous side- and backchannel sound. Snell’s SR30THX ($2,000) is one option, as is PSB’s Imagine S, which is part of a full PSB system that Sound + Vision reviewed in the December 2008 issue. (You can find that review at soundandvisionmag.com.) At $1,200 a pair, the Imagine S also doesn’t come cheap, but its ability to deliver 7.1 from a 5.1 speaker system means you essentially get two sets of surround speakers for the price of one.

-- Al Griffin

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Comments

[Kenneth Proctor]

For a setup with dipole speakers which would you prefer, setting them to dipole or bipole? Also, some dipoles can be wired separately, allowing a derived (in general) back surround signal to the back sides of the dipoles for 7.1 sound. Do you think a derived setting of this nature would yield any improvement upon straight dipole 5.1 hookup? (My room is 13 x 17.)